Timer for automatically defrosting refrigerators



D. MORRISON Nov. 21, 1950 TIMER FOR AUTOMATICALLY DEFROSTINGREFRIGERATORS Filed Sept. 24, 1948 2 Sheets-Sheet 1 v J/Vl/ENTOR. 2M

D. MORRISON Nov. 21, 1950 TIMER FOR AUTOMATICALLY DEFROSTINGREFRIGERATORS Filed Sept. 24, 1948 WWW/7gIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIII I Patented Nov. 21,i950 TIMER FOR aurom'rrcmv nsraos'rmo asrareana'roas David Morrison,Manitowoc, Wis., assignor to Paragon Electric. Company, Two Rivers,Wis.. a corporation of Wisconsin Application September 24, 1948, SerialNo. 50,902

1 6 Claims.

Refrigerators require defrosting from time to time, preferably oftenenough to prevent the accumulation of thick icy coatings; electricrefrigerators being at the present time commonly provided with switcheswhich the users'open whenever it is desired to defrost, and which, insome devices, automatically close after a predetermined period of timehas elapsed.

The object of the present invention is to make defrosting automatic atregular intervals so that the housewife or other person responsible fortaking care of a refrigerator is relieved entirely of the duty ofturning the current off and on.

Viewed in one aspect, my invention may be said to have for its object tocreate a simple, novel, and reliable timer for bringing about automaticdefrosting of a refrigerator indefinitely, at regular time intervals.

Viewed in a specific aspect, the present invention may be said to havefor its object the creation of a simple and novel timer provided with acontinuously operating motor which shall be adapted automatically toopen the electric circuit of a refrigerator atregular, predeterminedtimes and to keep it open for a predetermined period, which shall bereliablein operation and require little or no attention, and which maybe quickly and easily adjusted, both as to the length of the defrostingperiod and the times at which such period is to begin.

Viewed in still another aspect, my invention may be said to have for itsobject to produce a simple and novel switch mechanism capable ofeffecting quick openings and closings of a circuit and, in the preferredform, of varying the time interval between an opening and a closingoperation.

The various features of novelty whereby the present invention ischaracterized will hereinafter be pointed out with particularity in theclaims, but, for a full understanding of the invention and of itsobjects and advantages, reference may be had to the following detaileddescription taken I to be detached from the latter.

in connection with the accompanying drawings, I

the lower part of the casing being in elevation;

Fig. 5 is a section on a larger scale, on line 5-5 2 of Fig. 4; Fig. 6is a face view of a disc-like locking key used on the cam shaft; Figs.'7, 8 and 9 are sections taken, respectively, on lines 1-1, 8-4 and 9-9of Fig. 5; and Fig. 10 is a section on line Iii-l0 of Fig. 9.

In the drawings, 15 represents a suitable case ing having on the frontside a dial l6 and a, rotatable pointer 11 for cooperating with thedial. The dial is shown as suitably graduated for use with a pointerthat makes one revolution in twenty-four hours; but it will of course beunderstood that an instrument may be made wherein the pointer turns morerapidly or more slowly, in which case the dial will be designed to fitthe cycle chosen. For the sake of brevity the detailed description willbe confined to the particular form shown.

A suitable electric motor I! is mounted in the casing and, through agear train l9, drives a shaft 20 that protrudes through the front wallof the casing. A pointer II, that may be moved by hand, is firmlyfastened to the protruding end of the shaft, preferably in a manner thatpermits it The shaft is connected to the gear train in some conventionalmanner that permits it to be turned by the pointer while the gear trainis stationary. For a reason that will hereafter becom clear, the pointershould have the capacity to turn the shaft in one direction only, namelythat in which the motor turns it when running. In the arrangement shown,I employ the common one-way clutch construction containing a coiledspring that tightens on and locks two coaxial shafts together when it isattempted to turn them relatively to each other in one direction, butallows freerela- I tive movements in the opposite direction; spring 22being such a spring. The permissible movements of the pointer and theshaft 20, as viewed in Figs. 1, 2 and 3, are in the clockwise directiononly, which is the direction in which the motor turns the shaft.

Current for both'the motor i8 and an electric refrigerator is broughtinto the casing through a cable 24, the casing having a receptacle oroutlet 25 into which a cable, not shown, leading to the refrigerator maybe plugged. In the refrigerator circuit, of which wires 23 and 23 form apart,

is a switch that is mounted in the front part of a,sso,oss

. 3 I the plane in which the fingers move during the opening and closingof the switch being at right angles to said axis.

The upper ends 26 and 23, respectively, of fingers 26 and 21 arenarrowed so as to be spaced apart a little in the direction of thelength of the shaft. The fingers are provided with contact pieces 30,below the narrowed sections. for engagement with each other. The partsare so proportioned that these contact pieces are firmly pressedtogether in closed-circuit position by the fingers when the fingers areleft free to do so.

On the shaft are two disc-like electrically non-conductive cams 3| and32 which preferably are duplicates of each other. Cam 3| is in a planethat intersects the narrow upper end 23 of finger 26, whereas cam 32bears the same relation to the upper end 23 of finger 21. The low part34 of each cam is an arc of a circle, somewhat greater than asemicircle, in the arrangement shown; the radius of this circle beingsuch that the low part of each cam comes close to or barely touches theswitch finger with which it cooperates. The high portion 35 of each camis another, shorter arc of a larger circle, merged gradually at theleading end into the low part and terminating abruptly at the other endat the tip of an undercut nose-like section 36. Cam 32 is secured to theshaft so as to be compelled to rotate therewith. As best shown in Figs.9 and 10, the shaft is flattened for some distance inwardly from itsouter end, the fiattened part 20* meeting an abrupt shoulder 23 at itsinner end and the cam 32 is perforated with an opening having aconfiguration of the cross-section of the shaft portion 2|| so as torotate with same. A washer 31, pressed onto the shaft portion 20', holdsthe cam 32 in place and serves as a spacer between the same and cam 3|.As best shown in Fig. 5, cam 3| is fast on one end of a long flangedsleeve or bushing 36 that constitutes a hub therefor. In the forward endedge of this sleeve is a wide notch 33. The bushing, with the camattached thereto, is rotatable in either direction on the shaft.

The shaft contains a circumferential groove 40 at the forward end ofsleeve 33. When the washer-like key 4| shown in Fig. 6 is engaged inthis groove it looks the cams against movement lengthwise of the shaft.Surrounding sleeve 38, just inwardly from key 4|, is a washerlikecam-adjusting member 42 provided with a ing 44 that is set in notch 33,as best seen in Figs. and 7. Formed as part of member 42 is a radial arm45 the free end 46 of which is bent up to provide a manually operablefinger piece. Surrounding sleeve or hub 36 is a stiff coil spring 41,under initial compression, and bearing at one end against cam 3| whileits other end thrusts against cam-adjusting member 42. Thus member 42 ispressed firmly against key or abutment 4| while cam 3| is pressedagainst cam 32, or rather, the spacer 31 between the two cams. Thereforeconsiderable frictional resistance must be overcome before cam 3| can beturned relatively to cam 32. However, the coil spring 41 is notinfluenced by this friction because the parts in contact with the endsof the spring turn in unison and carry the spring along with them.

Pointer portion 2| is a, projecting rib or ledge on the front face orside of a thick disc 43. In the rear face of this disc is a recess 43wherein the key or abutment 4| is nested. In the edge 4 of this disc isan arcuate notch 66 of considerable angular width; the notch beingsufilciently deep to allow finger piece 43 to extend through and befreely movable within the same.

It will now be evident why the shaft must always turn in one directiononly. The noses 36 on the cams would catch on the switch fingers andperhaps damage the same if the shaft were turned in the counterclockwisedirection.

It is apparent that when the shaft turns in the clockwise direction,starting with the parts in the positions which they occupy in Fig. 2,the upper ends of the switch fingers are simply pressed toward the leftby the high portions 36 of the earns 32 and 3|, first finger 21 and thenfinger 26, so that the switch remains closed until one of the fingers,namely finger 21, is released and snaps back into its normalupright-position while the other finger 26 is still riding on the highportion 35 of its cam 3|, as in Fig. 3, for example; there being a quickbreaking of the circuit. The parts are so proportioned that when thelittle finger piece 43 of the cam-adjusting member 42 is at the lower.end of notch 33 as viewed in Fig. 1, the two cams 3| and 32 are in exactregistration with each other, the tip of one nose 36 being aligned withthe tip of the other. As the'finger piece 46 of the camadjusting member42 is shifted along the notch 50, the nose on cam 3| travels backward orin anti-clockwise rotation, moving the tips of the noses farther andfarther apart; the angular width of the notch determining the greatestextent of such separation. With the cams registering; the switch remainswhole twenty-four hours, for all practical purposes; that is because thecontacts 30 of switch fingers are in engagement with each other, duringthe rotation of the cams, and at the instant that both drop off the highsections 36 of their respective cams and presumably remain so during andafter the drop. When cam 3| is shifted so as to lag a little behind cam32 then, once in every twenty-four hours, finger 21 drops oil the highsection of cam 32 while finger 26 is still riding on the high section ofcam 3|, thus opening the switch as in Fig. 3. The length of time thatthe switch remains open may therefore be anything from zero to apredetermined maximum. The switch again closes with a. snap action whenfinger 26 snaps of! of the tip of the nose of cam 3| and causes itscontact 36 to sharply strike and engage the contact 30 on finger 21.

It is thus a very simple matter to achieve the most advantageous lengthof defrosting period in each individual case. The user needs only tomake a tentative adjustment and vary the time a little one way or theother, from day to day, until the most satisfactory defrosting period isattained.

With the pointer l1 and cams 3| and 32 preset in their relativepositions shown in Figs. 1 and 2. and with the pointer l1 and dial l6synchronized with the time of day, the defrosting period will startafter midnight at about 1:30 a. m. and will end when finger 26 isreleased from the high portion" ofcam 3|.

Although the primary purpose of my improved timer is for defrostingrefrigerators, it is obvious that the principle thereof may be usedwherever similar functions are to be carried out by a timer device.

While I have illustrated and described with particularity only a singlepreferred form of my closed during the invention, I do not desire to belimited to the exact details thus illustrated and described, but intendto cover all forms and arrangements that come within the definitions ofmy invention constituting the appended claims.

I claim:

i. In a timer, a switch comprising two long spring fingers, anchored atone end, that contact each other whenever left free to do so, arotatable shaft near said fingers and at right angles to the plane inwhich the fingers move as the switch opens and closes, a pointer on oneend of the shaft, 3, pair of like cams on said shaft, each finger havingat its free end a part that rides on one of the cams, each cam having alow section that leaves the corresponding finger free and a high sectionthat presses that finger farther away from the shaft, the advance endsof the sections merging gradually into the low sections and the trailingends of said high sections terminating abruptly, a motor for turning theshaft in one direction only, and a gear train, including a onewayclutch, connecting the motor to the shaft; whereby the clutch at alltimes allows the shaft to be turned in said direction by the pointer,independently of the motor, and at all times prevents the shaft fromturning in the opposite direction relatively to the motor.

2. A timer as set forth in claim 1, wherein one cam is fixed to theshaft, means frictionally holding the second cam on the shaft, whileallowing angular movement thereof relatively to the other said one camwhen a predetermined turning force is applied, and wherein a fingerpiece is operatively connected to the second cam to transmit thatturning force to the same.

3. In a timer, a switch comprising two long spring fingers, anchored atone end, that contact each other whenever left free to do so, arotatable shaft near said fingers and at right angles to the plane inwhich the fingers move as the switch opens and closes, a pair of likecams on said shaft, one cam being fixed on the shaft and the second cambeing frictionally held so as to yield under a predetermined turningforce in either direction and move angularly relatively to the firstcam, a

manually operable part on the second cam for applying thereto such aturning force, a pointer on one end of the shaft, each finger having atits free end a part that rides on one of the cams, each cam having a lowsection that leaves the corresponding finger free and a high sectionthat presses that finger farther away from the shaft, said high sectionsbeing of the same radius to cause the fingers to remain in contact witheach other while engaged with the high sections of the cams, a motoradapted to run continuously in one direction, and a connection betweenthe motor and the shaft to allow the shaft to be turned in saiddirection either by the motor, to open and close the switch, or by thepointer, independently of the motor, to set the timer and determine theangular position of the shaft at which the switch opens.

4. In a timer, a shaft, a switch beside the shaft, two switch-operatingcams on the shaft, one of the cams being fixed on the shaft and thesecond cam being loose, said shaft having an external removable abutmentat some distance from the second cam, a hub on the second cam extendinginto the vicinity of said abutment, a compression spring surroundingsaid hub and bearing at its ends against the near side of the second camand said abutment, respectively, to press the second cam into frictionalengagement with the first cam, and a finger piece attached to the saidhub for turning the second cam relatively to the other cam, a motor, agear train, including a one-way clutch, that constantly maintains aconnection between the motor and the shaft for driving the latter in onedirection only, and a pointer on the shaft to turn it in said directionindependently of the motor.

5. A timer as set forth in claim 4, wherein the hub has in its free endedge a notch and wherein the finger piece is part of and radiates from awasher-like piece provided with a lug that is entered in said notch inthe hub.

6. In a timer, a shaft, a switch beside the shaft, two switch-operatingcams on the shaft, one of the cams being fixed on the shaft and thesecond cam being loose, said shaft having an abutment thereon spacedfrom the second cam, a hub on the second cam extending into the vicinityof said abutment, a cam-adjustin member operatively connected with saidhub, a compression spring surrounding said hub and bearing at its endsagainst said second cam and said cam-adjusting member, respectively, topress said second cam into frictional engagement with the first cam, anda finger piece attached to said cam-adjusting member for turning saidsecond cam relatively to the first cam, a motor, a gear train, includinga one-way clutch, that constantly maintains a connection between themotor and the shaft for driving the latter in one direction only, and apointer on the shaft to turn it in said direction independently of themotor.

DAVID MORRISON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,124,045 Swensen July 19, 19382,190,603 Miller Feb. 13, 1940 2,354,368 Gallagher July 25, 1944

